I have heard that you are advised to balance the prop so as to limit vibration. Is there a way to do this without having to go out and purchase a prop balancer ??

Any suggestions welcome.

Regards, Michael

I don't worry about balancing props unless I see a real vibration problem. I have a balancer and rarely ever use it. In fact the only reason I have one is because it was a gift. It's nice, but unless you're flying in competition, it's not a "must have" item.

I have a balancer but I have never had a propeller out of balance. If you want to build one an easy way is a pin gage (hole gage) set on the hub of CD's

Stick with APC brand props. You should never need to balance one.

APC props do need to be balanced! 9 out of 10 are bad enough to require a fair amount of sanding! The only prop I did not have to balance was my Mezlik 18X8, but then at $35 it should already be balanced. For the time it takes to balance a prop, the end result is worth it. I have seen the result of a 20,000 rpm centrifuge being thrown out of balance (1/4 oz weight) for testing. It went threw a wall! Yes glow engines normally turn around 11,000 to 15,000 rpm., but imagine the vibration on the airframe at WOT. Those screws that won't stay tight or the needle valve that won't stay adjusted can all be caused by an unbalanced prop (yes, been there and done that!). The vibration you think you can't see is what will shorten the life of the plane, engine and radio gear. Vibration will also cause fuel foaming and can cause RX crystals to fail (that's why they tell you to wrap the RX in foam). What other people do with their stuff is their choice, I like to make it as right as it can be because I can't afford to keep replacing things when it could have been prevented.

No disrespect but I cannot believe this!

I have a GP magnetic prop balancer and I check every prop I use.

Zingers are pretty good but they do need to be balanced. The pack of TF power points I got from TH needed so much work I'm not sure I'll bother with them again.

People say that MAS shouldn't need to be balanced, I don't have any 2 blade paint stirrers hanging around so I can't comment.

I do, however, have a MAS 3-blade 8x6 which definitely looks like it has a heavy blade, but I'm not sure how to go about balancing a 3-blade.

For wood 2 blades I usually just sand the end of the heavy blade until the prop balances level, but there are articles which have been written on this subject that go into great detail about determining exactly which part of the prop blade is heavy and making adjustments in the appropriate place.

Trigger and all:
Your experience with Top Flight "Power Point" props is the same as mine. TF seems to be the worst of all brands, in regards to balance. And I don't remember ever having any prop balanced straight out of the box. Of any brand.

In the ten odd years since I've started balancing props I have had no radio failures. At all. I have had servos give a problem, but always due to what our British friends call an "Arrival." I call it a "Hard landing," but some unkind people call my hard landings crashes, requiring servo gear replacement to correct.

Balancing a three blade is a little harder than a two blade until you get the idea, then it's jus tthe same, except for one more blade.

Three Blade:

1) When the prop comes to rest, there usually will be a high blade, and a low blade. with the third at an intermediate angle. If it comes to rest with a blade straight down, skip to step 3).

One blade straight up is the most trouble. You have two blades that are equally heavy. Pick either low blade, and lighten it until you have the other heavy blade hanging straight down, giving two equally light blades. Go to step 3).

2) Consider the high blade as "A" and the low blade as "C." The other blade, obviously, is "B."

Lighten blade "B" until blade "C" hangs straight down. Now blades "A" and "B" are the same weight.

3) Lighten the lower blade until the prop is balanced. You have finished.

Additional note: If the prop has to be reamed, do it before balancing.

This is my way, and it works for me. Hope it helps.

If you are man enough to fly a twin,
. You've twice as many places for vibration to come in.

Bill.

Thanks for the description, I had to read it through a couple of times to be sure, but I've got it now

I think I might print that out for future reference....

Well to be honest, this is my first plane and have kinda followed the rules without running headlong into creating a small pile of balsa and servo's. The engine/prop combination that was supplied with the ARTF is a SC 40 MkII and a plastic prop (of unknown origin). I have seen somewhere that there are flexable props (for newbies like me) that will bend somewhat if they come into contact with mother earth. Would this be a good move ??

=================
Michael

Tigger:

You are more than welcome to copy it and send it to whomever you would like; it is not copy righted.

I think it is also a lot simpler than the method published in MAN (or RCM) a few months ago.

I fly almost exclusively three blade props, had to learn how to balance them in self defense. And self protection. Vibration problems can be a lot worse with twin engines. And yes, I am a member of the real modeling elite - the totally insane who scratch build twins. The folks who scratch four-engined monsters are, if possible, even more insane. Please note that I did not say build from plans.

Just another plane when built from plans,
. But when scratch built it's no other man's.

Bill.

Michael:
Flexible props are commonly used on planes with no landing gear, and they do save money.

But flexible props, lacking rigidity, cannot be as efficient as a prop that holds its shape under all aeordynamic loads.

You don't need that higher efficiency.

And, being brutal about it, your trainer is not expected to last long enough for the vibration to damage it. Just a fact of (trainer) life.

When your skill advances to the point that a crash is a truly rare event you'll want to do everything to maximize airframe life. I have several flying planes more than ten years old, and two that are more than 40 years old. Pictureattached is about 15 years old, worn out two engines, now has its third.

So don't be overly concerned about prop balancing right now, but do keep it in mind for later.

Expect to hit your props?
. The flexible ones are tops.

Bill.

Cheers for the advice Bill, going to source a flexible prop on the net as I really couldn't be arsed travelling the best part of 100 miles round trip to a decent model shop here in the North of Ireland

And lastly, "I do expect to hit my prop" should be regarded as lucky if thats all I hit


Michael

A Great Planes figertip prop balancer works great for me.....I keep it in my field box also, so that I have it at the field.....(not that I EVER break props!)

Mike